Skip to content

internal/strconv: fix ParseFloat for integer parts over 800 digits #82119

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
penglei wants to merge 1 commit into
base: master
Choose a base branch
from
+17 −3
Open

internal/strconv: fix ParseFloat for integer parts over 800 digits #82119

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 5 additions & 3 deletions src/internal/strconv/atof.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,7 @@ func (b *decimal) set(s string) (ok bool) {
// digits
sawdot := false
sawdigits := false
nd := 0 // number of significant digits
for ; i < len(s); i++ {
switch {
case s[i] == '_':
Expand All @@ -107,15 +108,16 @@ func (b *decimal) set(s string) (ok bool) {
return
}
sawdot = true
b.dp = b.nd
b.dp = nd
continue

case '0' <= s[i] && s[i] <= '9':
sawdigits = true
if s[i] == '0' && b.nd == 0 { // ignore leading zeros
if s[i] == '0' && nd == 0 { // ignore leading zeros
b.dp--
continue
}
nd++
if b.nd < len(b.d) {
b.d[b.nd] = s[i]
b.nd++
Expand All @@ -130,7 +132,7 @@ func (b *decimal) set(s string) (ok bool) {
return
}
if !sawdot {
b.dp = b.nd
b.dp = nd
}

// optional exponent moves decimal point.
Expand Down
12 changes: 12 additions & 0 deletions src/internal/strconv/atof_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,15 @@ var atoftests = []atofTest{
{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},
{"0x1.00000000000008" + strings.Repeat("0", 10000) + "1p0", "1.0000000000000002", nil},

// Integer part longer than the slow path's 800-digit decimal buffer.
{"1" + strings.Repeat("0", 799) + "e-673", "1e+126", nil},
{"1" + strings.Repeat("0", 800) + "e-674", "1e+126", nil},
{"1" + strings.Repeat("0", 826) + "e-700", "1e+126", nil},
{"1" + strings.Repeat("0", 826) + ".5e-700", "1e+126", nil},
// The nonzero tail sets trunc, and d and d+1 round differently near 1e126,
// so the optimized path falls back to the slow path too.
{"1" + strings.Repeat("0", 824) + "1e-699", "1e+126", nil},

// Halfway between x := math.Nextafter(1, 2) and math.Nextafter(x, 2)
// Round to even (up).
{"1.00000000000000033306690738754696212708950042724609375", "1.0000000000000004", nil},
Expand Down Expand Up @@ -371,6 +380,9 @@ var atof32tests = []atofTest{
{"1.000000059604644775390625" + strings.Repeat("0", 10000) + "1", "1.0000001", nil},
{"0x1.000001" + strings.Repeat("0", 10000) + "1p0", "1.0000001", nil},

// Integer part longer than the slow path's 800-digit decimal buffer.
{"1" + strings.Repeat("0", 824) + "1e-795", "1e+30", nil},

// largest float32: (1<<128) * (1 - 2^-24)
{"340282346638528859811704183484516925440", "3.4028235e+38", nil},
{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
Expand Down
Loading